Grace Design m902 Reference D/A headphone amplifier

In his bimonthly column, "The Fifth Element," John Marks has tried to identify pro-audio components that would be of interest to audiophiles. In his June 2005 episode, John wrote about Grace Design's m902 D/A headphone amplifier ($1695), the Colorado company's replacement for the 901, which had long been a favorite of his. Changes include: the handling of single-wire sample rates of up to 192kHz; unbalanced analog outputs, controlled by the front volume control, to allow the unit to be used as a preamplifier; a cross-feed processing circuit licensed from www.meier-audio.de; power-supply revisions; and the provision of a USB digital input, in addition to S/PDIF, AES/EBU, and TosLink.

"Grace Design's m902 impresses me as a preamplifier-DAC every bit as much as their 901 impressed me as a headphone amplifier," wrote JM last June. "All my favorite demo tracks, from Ella Fitzgerald to Mahler to Mary Black, were rendered with remarkable clarity and continuity. There was a roundness of tone, especially to the midrange, that was reminiscent of some of my peak audio experiences."

Comparing the m902 against his long-term reference, the Benchmark DAC-1 ($975), John was cautious in his conclusion: "At $1700, the Grace m902 costs 75% more than Benchmark's DAC-1. Is it nearly 'twice as good'? Probably not, by any rational calculus. But, using an emotional calculus, can the m902 provide twice the listening pleasure and twice the pride of ownership? I'd say 'yes.' Highly recommended."

Following his write-up, John sent me the Grace m902 for me to try for myself, as well as to put it through its technical paces on my test bench. I hooked it up as a digital processor in my current reference system—Ayre C-5xe universal player, Mark Levinson No.326S preamplifier, and Mark Levinson No.33H monoblocks driving, variously, Sonus Faber Amati Anniversario, Genesis 5.2, and Snell LCR7 loudspeakers, with Crystal Cable interconnects and AudioQuest DBS speaker cables—and did some extended listening.

With the Grace used in this manner, its volume control set to "94" to avoid overloading the preamplifier's input, my impressions were universally positive. Fed both CD data and 24-bit/96kHz data (when allowed by the disc) from the Ayre via AES/EBU, the Grace's presentation was airy, detailed, and grain-free. Soundstaging was spacious and stable.

For comparisons with other digital sources, I matched levels to within 0.1dB at 1kHz using the Levinson preamp's Input Offset function, which has 0.1dB steps. However, I did have some practical problems with the comparisons. While the Grace was free of hum when used on its own and fed an AES/EBU digital signal from the Ayre, I got ground loops when I used a more complicated setup for A/B comparisons. I was feeding the Ayre's digital datastream to a Mark Levinson No.30.6 processor, then using the Levinson's digital monitor and tape data outputs to feed both the Grace and the other processors under test. All connections were initially AES/EBU, using 1m lengths of Canare's low-cost cable, but the Grace hummed in this situation. Ultimately, I had to break the galvanic connection between the Levinson and the Grace by using a high-quality optical datalink, AudioQuest's OptiLink-5 TosLink cable.

The Levinson processor cost a whopping $17,500 when last available, and yes, it did sound slightly better than the tenth-the-price Grace m902! The two sounded very similar at high frequencies, though the slight chiff of breath noise that accompanies each note of the flute on the movement from Mozart's Flute Quartet, K.285, that I included on Editor's Choice (CD, Stereophile STPH016-2), was very slightly more emphasized through the Grace. The Levinson also threw a slightly deeper image, the solo clarinet on Mosaic (CD, Stereophile STPH015-2) sounding a little more spatially separated from the string quartet within the church acoustic than it did reproduced via the m902. It was a close-run thing, however, and without direct comparison I doubt that I could tell which processor was playing. Things were less ambiguous at low frequencies, though, where the more expensive processor had an edge, sounding more authoritative, with better bass definition.

Against the $5000 Ayre player's own analog outputs, both the Levinson and the Grace fell back a little in the midrange and treble, both sounding slightly more mechanical, less organic. The Ayre, however, lacked the Levinson's authority in the low bass, sounding more like the m902. Jerome Harris' acoustic bass guitar on Rendezvous (CD, Stereophile STPH013-2) has a wholeness to its character via the Levinson, with the transients properly integrated with the body of the instrument's tone, that was diluted by the two less expensive products. The Grace did have a warmer upper bass than the Ayre. Sometimes this was to the music's benefit; other times, it detracted. The rather overcooked bass guitar on Jack Johnson's "Times Like These," from On and On (CD, Island 980 709-2), sounded better defined on the Ayre, for example, than on the m902. The Grace did reproduce this cut's rather frightening acoustic guitar transients with the appropriate jump factor, however.

The literal benchmark for D/A converter performance at the approximate price level of the Grace m902 is Benchmark's DAC-1 ($975). The Benchmark is also a D/A headphone amplifier, with balanced and unbalanced line outputs as well as headphone jacks, but has digital inputs only. Though of similar size, the DAC-1 has a more utilitarian appearance than the m902.

With CD data, the differences were small, but that doesn't mean they weren't significant. Jack Johnson's rather throaty voice on On and On has been recorded with a bit of a mid-treble bark. The Benchmark reproduced this in full; the Grace softened its edge a little. On the other hand, the Benchmark painted transient edges on more naturally miked recordings—for example, my recording of the Mozart G-Minor Piano Quartet, K.478, on Bravo! (CD, Stereophile STPH014-2)—that little bit more effectively.

Peculiarly, the Benchmark's presentation sounded a little more distant than the Grace's. On this Mozart recording, I used a touch of Lexicon-derived reverberation to flesh out the over-dry sound that resulted from the rather close miking I'd had to employ. (For a discussion of this, see the article in our free online archives.) The Grace's reproduction of the reverb was actually closer to what I had intended when I mixed the CD, while the Benchmark was a little wetter; ie, more distantly balanced.

For my final comparisons between the Grace and the Benchmark, again I fed them from the Levinson, this time playing back 24-bit/88.2kHz master files of some of my recordings on my Apple PowerBook using a Metric Halo MIO2882 FireWire interface to provide an AES/EBU link to the Levinson.

At the time of writing, I am editing and mixing There Lies the Home, an album by Minnesotan choir Cantus of songs connected with the sea, scheduled to be released on CD early this summer. A particular favorite is Songs of the Sea, a collection of songs by English composer Sir Charles Stanford for baritone soloist with piano and male choir accompaniment. Soloist Kelvin Chan was in fine form for the June 2005 sessions, which were his swan song before leaving Cantus to pursue his love of opera performance. Over the Benchmark, both Kelvin and the sound of the piano on "Drake's Drum," the story of Sir Francis Drake awaiting the arrival of the Spanish Armada, were a little more reverberant than over the Grace. The m902 also sounded very slightly more warm than the DAC-1, perhaps due to more apparent energy in the lower mids, or perhaps to slightly less energy in the mid-treble. Both presentations were acceptable, but had I mixed with the Benchmark, I would gone for rather more of the closer mikes in the balance.

Overall, I enjoyed my time with the Grace m902. While it doesn't sound significantly better than the cheaper Benchmark, merely different, the fact that it offers analog as well as digital inputs and a remote control puts it in a different product class. I didn't do any serious headphone listening, so I asked Wes Phillips to add some thoughts below, but I highly recommend the m902 as a D/A preamp.—John Atkinson